I’m going to use the term small hydropower to refer to plants generating between 100 kilowatts and 30 megawatts of power. Others have different definitions.
For example, I’ve seen people use only two categories – large and small. They call anything less than 10 megawatts small.
However, I think it’s useful to have three categories: large, small and micro. These categories relate to how power might be generated in the real world and the cutoffs I suggest reflect that.
Classification of Hydroelectic Plants
Large is greater than 30 megawatts. These are large scale projects producing very significant amounts of power. They are generally run by large utility companies. Think Hoover Dam at more than 2,000 megawatts output.
At the other end of the scale are micro hydropower projects producting less than 100 kilowatts of power.
These projects are likely to be run by individuals or small organizations. For example, a homeowner with a stream running through their property might decide to set up a run-of-river system to provide at least part of their power.
Still on a micro scale, a farm or ranch might decide to do the same thing.
The 100 kilowatt cutoff reflects the real-world output of systems on this scale.
In between lies small hydroelectric.
As I mentioned, I define small hydroelectric projects as those that produce between 100 kilowatts and 30 megawatts of power. These types of projects are generally run by small communities or utilities.
Small plants often aren’t capable of supplying all the electric needs of the community, but they can supplement existing sources often at a cost savings.
As important, hydropower doesn’t produce any emissions.
Small hydropower can be either run-or-river or use a dam. I want to mention dams here.
An Untapped Resource
People who argue against hydropower as a significant source of electricity to meet our growing needs argue that all possible sites have already been explored. I don’t really believe that’s true, at least not with current technology and environmental concerns in mind.
Sites that authorities might not have considered economically viable with oil at $20 a barrel and only old technology turbines available might look a lot better now.
Leaving that aside, there’s an untapped resource. There are over 80,000 dams in the United States. Only about 2,000 are used to generate power.
One growing movement is for towns by small dams to set up a turbine to generate electricity. The infrastructure on the dam is already in place, saving that expense. And as this becomes more popular, the economics of scale are making the necessary turbines more affordable.
Also, some firms offer entire packages, reducing the need for custom engineering for the project. That, of course, reduces costs.
A Possible Vision
I like to imagine small hydroelectric plants becoming very affordable and environmentally friendly. They produce clean energy close to it’s point of use from a renewable resource.
Although an individual plant might be small, the cumulative effects could be large.
By the very nature of their small size, even systems using dams avoid many of the environmental issues of larger projects (flooding land, reducing oxygenation of the water, etc.). Further, if the dam is already there, the environmental impact had already happened. It seems wasteful not to harness the energy.
Of course, run of river systems don’t have these concerns.
Barring revolutionary technology, I think the answer to our search for environmentally-friendly, affordable alternative will come from a combination of a lot of sources. Small hydropower should be part of that answer
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Run of River Hydropower
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